Susan Stitt is sick of all the cancer. One neighbor has uterine cancer, another died of brain cancer. Stitt's mother has battled skin and breast cancer. A friend was recently diagnosed with colon cancer. Stitt could sit around feeling hopeless. Instead, she volunteered for the American Cancer Society's Cancer Prevention Study-3 (CPS-3), which is now recruiting participants nationwide. Stitt, 45, had her waist measured and blood drawn. And she filled out a questionnaire about her medical history, which she'll do every few years. If the research can help prevent cancer, she says, "I'll be so proud to be part of that winning team."

We should all be so determined. Cancer kills more than 1,500 Americans a day and costs over $200 billion a year in medical bills and lost productivity. While survival rates have improved significantly and new targeted drugs are transforming treatment, there's still plenty that doctors don't know about why healthy cells run amok. Prior studies have uncovered major links: smoking causes lung cancer; obesity ups the odds of colon, endometrial and postmenopausal breast cancer. Now researchers want to home in on their findings and uncover new preventive treatments.

That means you can do more than write a check for cancer research. For CPS-3 (cancer.org), researchers need 500,000 men and women between the ages of 30 and 65 who've never had cancer. (They've got 23,000 so far.) The goal of the study, which will follow participants for at least 20 years, is to figure out who gets cancer, who doesn't, and why. Weight and physical activity will be a major focus. If people feel safe in their local streets and parks, for example, are they more likely to exercise? Researchers will compare physical activity levels with ZIP codes to find out. The results may give scientists the ammunition they need to challenge urban planners to design healthier neighborhoods. Medications matter, too. It's known that aspirin reduces the incidence of colon cancer; CPS-3 will look for the effects, if any, of other drugs, like diabetes and hypertension medications. Unlike experimental-drug trials, which may improve a patient's health, CPS-3 won't provide a direct benefit to participants. "But," says study director Alpa Patel, "there is to loved ones and definitely to the next generation."

Many prevention trials are looking for people who've already beaten cancer or are at a higher risk of developing it (you're a smoker, you have a family history). Diana Browning, who was treated for endometrial cancer in 2004, enrolled in a behavioral-intervention study at M.D. Anderson Cancer Center in Houston (mdanderson.org), in which researchers hope to determine strategies—goal-setting? telephone counseling?—that will motivate women to stick with a workout plan. Browning's participation will help others, and she's helped herself by losing 45 pounds.

One day, cancer vaccines might be a reality. But drugs and other compounds already on the market could help much sooner, and the National Cancer Institute is sponsoring dozens of clinical trials (cancer.gov) to test them. Most are studying people at increased risk. Examples: can an acid-reflux drug prevent Barrett's esophagus, a precursor to esophageal cancer, from progressing? Does calcium with vitamin D prevent colon polyps better than calcium alone in patients who've already had a precancerous growth? "People talk about cure all the time," says the NCI's Dr. Leslie Ford. "But the goal is people never getting diagnosed."

The key may be identifying subtle genetic changes that affect risk, says M.D. Anderson's Dr. Ernest Hawk. Ultimately, oncologists want to ward off cancer by measuring biomarkers, the way cardiologists prevent heart attacks by tracking blood pressure and cholesterol. Let's help them get there.

© 2008